US2022413031A1PendingUtilityA1
Line double-end steady-state quantity distance measuring method and system based on amplitude-comparison principle
Assignee: CHINA ELECTRIC POWER RES INSTITUTE COMPANY LIMITEDPriority: Jan 17, 2020Filed: Jul 8, 2020Published: Dec 29, 2022
Est. expiryJan 17, 2040(~13.5 yrs left)· nominal 20-yr term from priority
Inventors:Yarong GuoXingguo WangZexin ZhouYing LiangGuosheng YangHuanzhang LiuDingxiang DuYong LiShuyang WangQi ChengHong-Xi CaoZhengguang Chen
G01R 31/088Y04S10/52G01R 31/085
39
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Claims
Abstract
A line double-end steady-state quantity distance measuring method and system based on an amplitude-comparison principle. According to the method and system, voltage values and current values of both sides of a line before and after a fault are collected ( 102 ), a voltage variable quantity and a current variable quantity of both sides of the line are calculated ( 103 ), and after a voltage phasor value and a current phasor value are determined according to the voltage variable quantity and the current variable quantity ( 104 ), the position of a short-circuit point is determined by performing iterative calculation on the voltage of the short-circuit point. The method is simple in principle, and can accurately recognize a fault point, achieving precise distance measurement of lines.
Claims
exact text as granted — not AI-modified1 . A line double-end steady-state quantity distance measuring method based on an amplitude-comparison principle, comprising:
at step 1, collecting voltage values and current values, after an overhead line-cable hybrid transmission line is faulted, of both sides of the line, and voltage values and current values of both sides of the line of one cycle before the line is faulted; wherein both sides of the line are respectively a side M and a side N; at step 2, determining voltage value variations according to the collected voltage values of both sides of the line before and after the line is faulted, and determining current value variations according to the collected current values of both sides of the line before and after the line is faulted; at step 3, calculating voltage phasor values of both sides of the line by performing Fourier transformation on the voltage value variations of both sides of the line, and calculating current phasor values of both sides of the line by performing the Fourier transformation on the current value variations of both sides of the line; at step 4, calculating voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of a compensation point according to a distance x i from the compensation point to the side M of the line after the line is faulted, the voltage phasor values and the current phasor values of both sides of the line, a length L 1 of an overhead line on the side M, a length L 3 of an overhead line on the side N, a length L 2 of a cable, a wave impedance Z cT and a propagation coefficient γ T of the overhead line, and a wave impedance Z cC and a current propagation coefficient γ C of the cable; wherein an initial value of i is 1, and φ is any phase in a three-phase circuit, φ=A,B,C; at step 5, determining a distance x i+1 from the compensation point to the side M of the line based on a set distance measuring model according to the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point; and at step 6, setting i=i+1; determining that a distance measuring result is a distance x N+1 from the compensation point to the side M of the line in case of i>R; and turning back to the step 4 in case of i≤R; wherein R is a number of iterations.
2 . The method of claim 1 , wherein before collecting the voltage values and the current values of both sides of the line after the overhead line-cable hybrid transmission line is faulted, further comprising:
setting distance measuring parameters, determining the wave impedance Z cT and the propagation coefficient γ T of the overhead line, and determining the wave impedance Z cC and the current propagation coefficient γ C of the cable; wherein the distance measuring parameters comprise a length L of the transmission line, the length L 1 of the overhead line on the side M, the length L 3 of the overhead line on the side N, the length L 2 of the cable, the number R of iterations, and an initial distance x 1 from the compensation point to the side M; wherein calculation formulas for the wave impedance Z cT and the propagation coefficient γ T of the overhead line, and the wave impedance Z cC and the current propagation coefficient γ C of the cable are respectively:
Z cT = 𝓏 T y T , γ T = 𝓏 T y T , Z cC = 𝓏 C y C , γ C =√{square root over (z C y C )};
wherein z T is a unit impedance of the overhead line; y T is a unit admittance of the overhead line; z C is a unit impedance of the cable; and y C is a unit admittance of the cable.
3 . The method of claim 1 , wherein calculation formulas for calculating the voltage value variations according to the collected voltage values of both sides of the line before and after the line is faulted, and calculating the current value variations according to the collected current values of both sides of the line before and after the line is faulted are:
Δ u φM ( t qd +kT+t )= u φM ( t qd +kT+t )− u φM ( t qd −T+t ),
Δ u φN ( t qd +kT+t )= u φN ( t qd +kT+t )− u φN ( t qd −T+t ),
Δ i φM ( t qd +kT+t )= i φM ( t qd +kT+t )− i φM ( t qd −T+t ),
Δ i φN ( t qd +kT+t )= i φN ( t qd +kT+t )− i φN ( t qd −T+t );
wherein both sides of the line are respectively the side M and the side N; t qd is a distance measuring start moment; T is a power frequency cycle, 0<t<T , k≥1, φ=A,B,C; u φM (t qd +kT+t) and u φN (t qd +kT+t) are respectively the collected voltage values of the side M and the side N of the line of phase φ after the fault occurs; u φM (t qd −T+t) and u φN (t qd −T+t) are respectively the collected voltage values of the side M and the side N of the line of phase φ of one cycle before the fault occurs; Δu φM (t qd +kT+t) and uΔ φN (t qd +kT+t) are respectively the voltage variations of the side M and the side N of the line of phase φ after the phase occurs; i φM (t qd +kT+t) and i φN (t qd +kT+t) are respectively the collected current values of the side M and the side N of the line of phase φ after the fault occurs; i φM (t qd −T+t) and i φN (t qd −T+t) are respectively the collected current values of the side M and the side N of the line of phase φ of one cycle before the fault occurs; and Δi φM (t qd +kT+t) and Δi φN (t qd +kT+t) are respectively the current variations of the side M and the side N of the line of phase φ after the fault occurs.
4 . The method of claim 2 , wherein calculation formulas for calculating the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point according to the distance x i from the compensation point to the side M of the line after the line is faulted, the voltage phasor values and the current phasor values of both sides of the line, the length L 1 of the overhead line on the side M, the length L 3 of the overhead line on the side N, the length L 2 of the cable, the wave impedance Z cT and the propagation coefficient γ T of the overhead line, and the wave impedance Z cC and the current propagation coefficient γ C of the cable comprises:
when the compensation point is at an overhead line section on the side M, the distance from the compensation point to the side M of the line is x i , and the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point are calculated by using following calculation formulas:
{
Δ
I
.
φ
N
1
=
Δ
I
.
φ
N
cosh
(
γ
T
L
3
)
-
Δ
U
.
φ
N
Z
cT
sinh
(
γ
T
L
3
)
Δ
U
.
φ
N
1
=
Δ
U
.
φ
N
cosh
(
γ
T
L
3
)
-
Δ
I
.
φ
N
Z
cT
sinh
(
γ
T
L
3
)
,
{
Δ
I
.
φ
M
1
=
Δ
I
.
φ
N
1
cosh
(
γ
C
L
2
)
-
Δ
U
.
φ
N
1
Z
cC
sinh
(
γ
C
L
2
)
Δ
U
.
φ
M
1
=
Δ
U
.
φ
N
1
cosh
(
γ
C
L
2
)
-
Δ
I
.
φ
N
1
Z
cC
sinh
(
γ
C
L
2
)
,
{
Δ
U
.
φ
Mxi
=
Δ
U
.
φ
M
cosh
(
γ
T
x
)
-
Δ
I
.
φ
M
Z
cT
sinh
(
γ
T
x
)
Δ
U
.
φ
Nxi
=
Δ
U
.
φ
M
1
cosh
[
γ
T
(
L
1
-
x
)
]
-
Δ
I
.
φ
M
1
Z
cT
sinh
[
γ
T
(
L
1
-
x
)
]
;
when the compensation point is at a cable section, the distance from the compensation point to the side M of the line is x i , and the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point are calculated by using following calculation formulas:
{
Δ
I
.
φ
N
1
=
Δ
I
.
φ
N
cosh
(
γ
T
L
3
)
-
Δ
U
.
φ
N
Z
cT
sinh
(
γ
T
L
3
)
Δ
U
.
φ
N
1
=
Δ
U
.
φ
N
cosh
(
γ
T
L
3
)
-
Δ
I
.
φ
N
Z
cT
sinh
(
γ
T
L
3
)
,
{
Δ
I
.
φ
M
1
=
Δ
I
.
φ
M
cosh
(
γ
T
L
1
)
-
Δ
U
.
φ
M
Z
cT
sinh
(
γ
T
L
1
)
Δ
U
.
φ
M
1
=
Δ
U
.
φ
M
cosh
(
γ
T
L
1
)
-
Δ
I
.
φ
M
Z
cT
sinh
(
γ
T
L
1
)
,
{
Δ
U
.
φ
Mxi
=
Δ
U
.
φ
M
1
cosh
[
γ
C
(
x
-
L
1
)
]
-
Δ
I
.
φ
M
1
Z
cC
sinh
[
γ
C
(
x
-
L
1
)
]
Δ
U
.
φ
Nxi
=
Δ
U
.
φ
N
1
cosh
[
γ
C
(
L
1
+
L
2
-
x
)
]
-
Δ
I
.
φ
N
1
Z
cC
sinh
[
γ
C
(
L
1
+
L
2
-
x
)
]
;
when the compensation point is at the overhead line section on the side N, the distance from the compensation point to the side M of the line is x i , and the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point are calculated by using following calculation formulas:
{
Δ
I
.
φ
M
1
=
Δ
I
.
φ
M
cosh
(
γ
T
L
1
)
-
Δ
U
.
φ
M
Z
cT
sinh
(
γ
T
L
1
)
Δ
U
.
φ
M
1
=
Δ
U
.
φ
M
cosh
(
γ
T
L
1
)
-
Δ
I
.
φ
M
Z
cT
sinh
(
γ
T
L
1
)
,
{
Δ
I
.
φ
N
1
=
Δ
I
.
φ
M
1
cosh
(
γ
C
L
2
)
-
Δ
U
.
φ
M
1
Z
cC
sinh
(
γ
C
L
2
)
Δ
U
.
φ
N
1
=
Δ
U
.
φ
M
1
cosh
(
γ
C
L
2
)
-
Δ
I
.
φ
M
1
Z
cC
sinh
(
γ
C
L
2
)
,
{
Δ
U
.
φ
Mxi
=
Δ
U
.
φ
N
1
cosh
[
γ
T
(
x
-
L
1
-
L
2
)
]
-
Δ
I
.
φ
N
1
Z
cT
sinh
[
γ
T
(
x
-
L
1
-
L
2
)
]
Δ
U
.
φ
Nxi
=
Δ
U
.
φ
N
cosh
[
γ
T
(
L
1
+
L
2
+
L
3
-
x
)
]
-
Δ
I
.
φ
N
Z
cT
sinh
[
γ
T
(
L
1
+
L
2
+
L
3
-
x
)
]
;
wherein M 1 and N 1 are respectively connections between the overhead line of the side M of the line and the cable as well as between the side N of the line and the cable; Δ{dot over (U)} φM1 and Δ{dot over (U)} φN1 are respectively the voltage phasor values at the position M 1 and the position N 1 of the phase φ of the transmission line; Δ{dot over (U)} φM and Δ{dot over (U)} φN are respectively the voltage phasor values of the side M and the side N of the phase φ of the transmission line; Δİ φM1 and Δİ φN1 are respectively the current phasor values at the position M 1 and the position N 1 of the phase φ of the transmission line; Δİ φM and Δİ φN are respectively the current phasor values of the side M and the side N of the phase φ of the transmission line; Δ{dot over (U)} φMxi is the voltage of the compensation point calculated and determined according to the voltage phasor value and the current phasor value close to the side M of the compensation point; and Δ{dot over (U)} φNxi is the voltage of the compensation point calculated and determined according to the voltage phasor value and the current phasor value close to the side N of the compensation point.
5 . The method of claim 2 , wherein during determining the distance x i+1 from the compensation point to the side M of the line based on the set distance measuring model according to the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point, a calculation formula of the distance measuring model is:
x
i
+
1
{
x
i
-
L
2
i
+
1
❘
"\[LeftBracketingBar]"
Δ
U
.
φ
Mxi
❘
"\[RightBracketingBar]"
≥
❘
"\[LeftBracketingBar]"
Δ
U
.
φ
Nxi
❘
"\[RightBracketingBar]"
x
i
+
L
2
i
+
1
❘
"\[LeftBracketingBar]"
Δ
U
.
φ
Mxi
❘
"\[RightBracketingBar]"
<
❘
"\[LeftBracketingBar]"
Δ
U
.
φ
Nxi
❘
"\[RightBracketingBar]"
;
wherein L is a length of the transmission line.
6 . A line double-end steady-state quantity distance measuring system based on an amplitude-comparison principle, comprising:
a data acquisition component, configured to collect voltage values and current values, after an overhead line-cable hybrid transmission line is faulted, of both sides of the line, and voltage values and current values of both sides of the line of one cycle before the line is faulted; wherein both sides of the line are respectively a side M and a side N; a first calculator, configured to determine voltage value variations according to the collected voltage values of both sides of the line before and after the line is faulted, and determine current value variations according to the collected current values of both sides of the line before and after the line is faulted; a second calculator, configured to calculate voltage phasor values of both sides of the line by performing Fourier transformation on the voltage value variations of both sides of the line, and calculate current phasor values of both sides of the line by performing the Fourier transformation on the current value variations of both sides of the line; a third calculator, configured to calculate voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of a compensation point according to a distance x i from the compensation point to the side M of the line after the line is faulted, the voltage phasor values and the current phasor values of both sides of the line, a length L 1 of an overhead line on the side M, a length L 3 of an overhead line on the side N, a length L 2 of a cable, a wave impedance Z cT and a propagation coefficient γ T of the overhead line, and a wave impedance Z cC and a current propagation coefficient γ C of the cable; wherein an initial value of i is 1, and φ is any phase in a three-phase circuit, φ=A,B,C; and a result determination component, configured to determine a distance x i+1 from the compensation point to the side M of the line based on a set distance measuring model according to the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point, set i=i+1, determine that a distance measuring result is a distance x N+1 from the compensation point to the side M of the line in case of i>R, and turn back to the third calculator in case of i≤R; wherein R is a number of iterations.
7 . The system of claim 6 , further comprising an initialization component; wherein the initialization component is configured to set distance measuring parameters, determine the wave impedance Z cT and the propagation coefficient γ T of the overhead line, and determine the wave impedance Z cC an the current propagation coefficient γ C of the cable; wherein the distance measuring parameters comprises a length L of the transmission line, the length L 1 of the overhead line on the side M, the length L 3 of the overhead line on the side N, the length L 2 of the cable, the number R of iterations, and an initial distance x 1 from the compensation point to the side M;
wherein calculation formulas for the wave impedance Z cT and the propagation coefficient γ T of the overhead line, and the wave impedance Z cC and the current propagation coefficient γ C of the cable are respectively:
Z cT = 𝓏 T y T , γ T = 𝓏 T y T , Z cC = 𝓏 C y C , γ C =√{square root over (z C y C )};
wherein z T is a unit impedance of the overhead line; y T is a unit admittance of the overhead line; z C is a unit impedance of the cable; and y C is a unit admittance of the cable.
8 . The system of claim 6 , wherein the first calculator is configured to use calculation formulas:
Δ u φM ( t qd +kT+t )= u φM ( t qd +kT+t )− u φM ( t qd −T+t ),
Δ u φN ( t qd +kT+t )= u φN ( t qd +kT+t )− u φN ( t qd −T+t ),
Δ i φM ( t qd +kT+t )= i φM ( t qd +kT+t )− i φM ( t qd −T+t ),
Δ i φN ( t qd +kT+t )= i φN ( t qd +kT+t )− i φN ( t qd −T+t );
wherein both sides of the line are respectively the side M and the side N; t qd is a distance measuring start moment; T is a power frequency cycle, 0<t<T, k≥1, φ=A,B,C; u φM (t qd +kT+t) and u φN (t qd +kT+t) are respectively the collected voltage values of the side M and the side N of the line of phase φ after the fault occurs; u φM (t qd −T+t) and u φN (t qd −T+t) are respectively the collected voltage values of the side M and the side N of the line of phase φ of one cycle before the fault occurs; Δu φM (t qd +kT+t) and Δu φN (t qd +kT+t) are respectively the voltage variations of the side M and the side N of the line of phase φ after the phase occurs; i φM (t qd +kT+t) and i φN (t qd +kT+t) are respectively the collected current values of the side M and the side N of the line of phase φ after the fault occurs; i φM (t qd −T+t) and i φN (t qd −T+t) are respectively the collected current values of the side M and the side N of the line of phase φ of one cycle before the fault occurs; and Δi φM (t qd +kT+t) and Δi φN (t qd +kT+t) are respectively the current variations of the side M and the side N of the line of phase φ after the fault occurs.
9 . The system of claim 7 , wherein the third calculator is configured to use calculation formulas:
when the compensation point is at the overhead line section on the side M, the distance from the compensation point to the side M of the line is x i , and the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point are calculated by using following calculation formulas:
{
Δ
I
.
φ
N
1
=
Δ
I
.
φ
N
cosh
(
γ
T
L
3
)
-
Δ
U
.
φ
N
Z
cT
sinh
(
γ
T
L
3
)
Δ
U
.
φ
N
1
=
Δ
U
.
φ
N
cosh
(
γ
T
L
3
)
-
Δ
I
.
φ
N
Z
cT
sinh
(
γ
T
L
3
)
,
{
Δ
I
.
φ
M
1
=
Δ
I
.
φ
N
1
cosh
(
γ
C
L
2
)
-
Δ
U
.
φ
N
1
Z
cC
sinh
(
γ
C
L
2
)
Δ
U
.
φ
M
1
=
Δ
U
.
φ
N
1
cosh
(
γ
C
L
2
)
-
Δ
I
.
φ
N
1
Z
cC
sinh
(
γ
C
L
2
)
,
{
Δ
U
.
φ
Mxi
=
Δ
U
.
φ
M
cosh
(
γ
T
x
)
-
Δ
I
.
φ
M
Z
cT
sinh
(
γ
T
x
)
Δ
U
.
φ
Nxi
=
Δ
U
.
φ
M
1
cosh
[
γ
T
(
L
1
-
x
)
]
-
Δ
I
.
φ
M
1
Z
cT
sinh
[
γ
T
(
L
1
-
x
)
]
;
when the compensation point is at the cable section, the distance from the compensation point to the side M of the line is x i , and the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point are calculated by using following calculation formulas:
{
Δ
I
.
φ
N
1
=
Δ
I
.
φ
N
cosh
(
γ
T
L
3
)
-
Δ
U
.
φ
N
Z
cT
sinh
(
γ
T
L
3
)
Δ
U
.
φ
N
1
=
Δ
U
.
φ
N
cosh
(
γ
T
L
3
)
-
Δ
I
.
φ
N
Z
cT
sinh
(
γ
T
L
3
)
,
{
Δ
I
.
φ
M
1
=
Δ
I
.
φ
M
cosh
(
γ
T
L
1
)
-
Δ
U
.
φ
M
Z
cT
sinh
(
γ
T
L
1
)
Δ
U
.
φ
M
1
=
Δ
U
.
φ
M
cosh
(
γ
T
L
1
)
-
Δ
I
.
φ
M
Z
cT
sinh
(
γ
T
L
1
)
,
{
Δ
U
.
φ
Mxi
=
Δ
U
.
φ
M
1
cosh
[
γ
C
(
x
-
L
1
)
]
-
Δ
I
.
φ
M
1
Z
cC
sinh
[
γ
C
(
x
-
L
1
)
]
Δ
U
.
φ
Nxi
=
Δ
U
.
φ
N
1
cosh
[
γ
C
(
L
1
+
L
2
-
x
)
]
-
Δ
I
.
φ
N
1
Z
cC
sinh
[
γ
C
(
L
1
+
L
2
-
x
)
]
;
when the compensation point is at the overhead line section on the side N, the distance from the compensation point to the side M of the line is x i , and the voltages Δ{dot over (U)} φMxi and Δ{dot over (U)} φNxi of the compensation point are calculated by using following calculation formulas:
{
Δ
I
.
φ
M
1
=
Δ
I
.
φ
M
cosh
(
γ
T
L
1
)
-
Δ
U
.
φ
M
Z
cT
sinh
(
γ
T
L
1
)
Δ
U
.
φ
M
1
=
Δ
U
.
φ
M
cosh
(
γ
T
L
1
)
-
Δ
I
.
φ
M
Z
cT
sinh
(
γ
T
L
1
)
,
{
Δ
I
.
φ
N
1
=
Δ
I
.
φ
M
1
cosh
(
γ
C
L
2
)
-
Δ
U
.
φ
M
1
Z
cC
sinh
(
γ
C
L
2
)
Δ
U
.
φ
N
1
=
Δ
U
.
φ
M
1
cosh
(
γ
C
L
2
)
-
Δ
I
.
φ
M
1
Z
cC
sinh
(
γ
C
L
2
)
,
{
Δ
U
.
φ
Mxi
=
Δ
U
.
φ
N
1
cosh
[
γ
T
(
x
-
L
1
-
L
2
)
]
-
Δ
I
.
φ
N
1
Z
cT
sinh
[
γ
T
(
x
-
L
1
-
L
2
)
]
Δ
U
.
φ
Nxi
=
Δ
U
.
φ
N
cosh
[
γ
T
(
L
1
+
L
2
+
L
3
-
x
)
]
-
Δ
I
.
φ
N
Z
cT
sinh
[
γ
T
(
L
1
+
L
2
+
L
3
-
x
)
]
;
wherein M 1 and N 1 are respectively connections between the overhead line of the side M of the line and the cable as well as between the side N of the line and the cable; Δ{dot over (U)} φM1 and Δ{dot over (U)} φN1 are respectively the voltage phasor values at the position M 1 and the position N 1 of the phase φ of the transmission line; Δ{dot over (U)} φM and Δ{dot over (U)} φN are respectively the voltage phasor values of the side M and the side N of the phase φ of the transmission line; Δİ φM1 and Δİ φN1 are respectively the current phasor values at the position M 1 and the position N 1 of the phase φ of the transmission line; Δİ φM and Δİ φN are respectively the current phasor values of the side M and the side N of the phase φ of the transmission line; Δ{dot over (U)} φMxi is the voltage of the compensation point calculated and determined according to the voltage phasor value and the current phasor value close to the side M of the compensation point; and Δ{dot over (U)} φNxi is the voltage of the compensation point calculated and determined according to the voltage phasor value and the current phasor value close to the side N of the compensation point.
10 . The system of claim 7 , wherein a calculation formula, adopted by the result determination component, for the distance measuring model is:
x
i
+
1
{
x
i
-
L
2
i
+
1
❘
"\[LeftBracketingBar]"
Δ
U
.
φ
Mxi
❘
"\[RightBracketingBar]"
≥
❘
"\[LeftBracketingBar]"
Δ
U
.
φ
Nxi
❘
"\[RightBracketingBar]"
x
i
+
L
2
i
+
1
❘
"\[LeftBracketingBar]"
Δ
U
.
φ
Mxi
❘
"\[RightBracketingBar]"
<
❘
"\[LeftBracketingBar]"
Δ
U
.
φ
Nxi
❘
"\[RightBracketingBar]"
;
wherein L is a length of the transmission line.Join the waitlist — get patent alerts
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